Rare earth materials as coating compositions for conductors

ABSTRACT

A conductor includes a core with at least one conductive filament, and a coating deposited on a surface of the core. The coating is made of a rare earth material that includes at least one rare earth element selected from the group consisting of Lanthanum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm), Europium (Eu), Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium (Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb), Lutetium (Lu), Scandium (Sc) and Yttrium (Yt).

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/008,872, filed Jun. 6, 2014, entitled “Rare Earth Materials asCoating Compositions for Conductors,” the entire disclosure of which isincorporated by reference herein.

FIELD

The present invention relates to coatings for conductors, such asconductors for overhead power transmission lines.

BACKGROUND

Overhead power transmission lines provide electrical power transmissionand distribution over great distances. The power transmission lines aretypically supported via towers and/or poles so as to be suspended at asafe distance from the ground so as to prevent dangerous contact with anenergized line during power transmission operations.

It is desirable to provide an adequate coating for conductors that isresistant to accumulation of ice as well as resistant to wear from theoutside environment while providing adequate insulating properties tothe conductor.

SUMMARY

A conductor comprises an elongate central or core member comprising oneor more conductive filaments and a coating composition surrounding atleast a portion of the central member, where the coating compositioncomprises a rare earth material. The rare earth material includes atleast one rare earth element selected from the group consisting ofLanthanum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd),Promethium (Pm), Samarium (Sm), Europium (Eu), Gadolinium (Gd), Terbium(Tb), Dysprosium (Dy), Holmium (Ho), Erbium (Er), Thulium (Tm),Ytterbium (Yb), Lutetium (Lu), Scandium (Sc) and Yttrium (Yt).

In an example embodiment, the conductor comprises an overhead conductorincluding a plurality of filaments bundled in any suitable manner withinthe core member.

In another example embodiment, the conductor is coated with the coatingcomposition utilizing a cold spray deposition process.

These and/or other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a side view in partial cross section depicting analuminum conductor steel supported (ACSS) round wire (RW) conductorcable to which a coating as described herein is applied.

FIG. 2 depicts a side view in partial cross section depicting analuminum conductor steel supported (ACSS) trap wire (TW) conductor cableto which a coating as described herein is applied.

FIG. 3 schematically depicts an example process for depositing a rareearth coating on a conductor surface.

DETAILED DESCRIPTION

Conductors are described herein that include coating compositionscomprising a rare earth material, where the rare earth material includesat least one rare earth element. In addition to insulating propertiesfor the conductor, the rare earth material in the coating compositionprovides sufficient hydrophobic properties as well as sufficientanti-icing properties to inhibit or prevent a build-up of ice on theconductor during exposure to the elements in outdoor environments.

The rare earth material can include any one or a combination of rareearth elements selected from the group consisting of Lanthanum (La),Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm),Samarium (Sm), Europium (Eu), Gadolinium (Gd), Terbium (Tb), Dysprosium(Dy), Holmium (Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb), Lutetium(Lu), Scandium (Sc) and Yttrium (Yt). In example embodiments, the rareearth material can include La, Ce, Gd, Er, Tm and combinations thereof.

The rare earth material can include one or more rare earth elements intheir elemental form. Alternatively, the rare earth material can includeone or more rare earth oxides. Further still, the rare earth materialcan include combinations of one or more rare earth elements in theirelemental form combined with one or more rare earth oxides. Somenon-limiting examples of rare earth oxides for use in the rare earthmaterial include La₂O₃, CeO₂, Gd₂O₃, Er₂O₃, and Tm₂O₃.

Optionally, the rare earth material can also include additionalcomponents other than rare earth elements or rare earth oxides. Forexample, one or more additives can be provided to the rare earthmaterial to enable or enhance cohesion of particles within the coatingas well as adhesion and/or stability of the rare earth material to theconductor surface. Some non-limiting examples for additional componentsinclude aluminum (Al) and zinc (Zn). In particular, certain rare earthelement particles or rare earth oxide particles may not adhere well toeach other such that, upon deposition on a conductor surface, theresultant coating may exhibit some amount of flaking or loss ofparticles from the coating. An additive such as Al or Zn, provided in asuitable amount within the rare earth material, will function as anadhesive between rare earth element particles and/or rare earth oxideparticles that enhances cohesion and stability of the coating. The rareearth material can also include any other suitable additives as desiredfor a particular application. Alternatively, the rare earth material canbe substantially free of any additive. For example, the rare earthmaterial can comprise substantially entirely one or more rare earthelements and/or one or more rare earth oxides such that the rare earthmaterial contains less than 5% by volume (e.g., no more than 1% byvolume, or no more than 0.5% by volume) of any other component.

The conductor can be coated with the rare earth material in any suitablemanner that facilitates an acceptable adhesion of the rare earthmaterial to the conductor surface. Some examples for coating a rareearth material to the surface of a conductor include wet or thermalspray techniques (e.g., sputtering, plasma spraying, arc spraying,chemical vapor deposition, etc.) and dry techniques (e.g., cold spraydeposition).

A conductor to be coated with the rare earth material is typicallyelongated and has a non-planar surface area, such as a rounded ormulti-faceted outer peripheral surface area (e.g., the cross-section ofthe conductor may be circular or multi-faceted, such as square,hexagonal or octagonal) extending around the circumference or exteriorof the conductor. The rare earth material is coated around at least aportion of the rounded or multi-faceted peripheral surface area,preferably the entire periphery and over a suitable length of theconductor. The conductor can have any suitable length. For example, theconductor can have a substantially continuous length in environments inwhich the conductor is configured to extend great distances (e.g., anoverhead power transmission conductor configured to extend for miles orkilometers).

In example embodiments, a cold spray deposition process is utilized tocoat the surface of a conductor with the rare earth material. In a coldspray deposition process, a material coating is applied by impacting asolid powder of material at a high velocity against a substrate surfacethat causes particles within the solid powder to plastically deform andadhere to the substrate surface. Solid powders having particle sizes inthe range, e.g., of about 1 micrometer to about 50 micrometers incross-section are contacted with a carrier gas and accelerated insupersonic gas jets through a nozzle toward the substrate surface athigh velocities (e.g., velocities from about 500 meters per second toabout 1000 meters per second). The carrier gas can be, e.g., nitrogen orhelium. To achieve a uniform thickness along the substrate surface, oneor both of the spraying nozzle and substrate is moved in relation to theother. In addition, multiple spraying nozzles can also be utilized tocoat the surface. The carrier gas can be heated to a temperature that isless than the melting point of the solid powder material, such thatdeposition occurs with the powder remaining in a solid state. Thekinetic energy of the particles, supplied by the expansion of the gasemerging from the nozzle, is converted to plastic deformation energyduring bonding.

As previously noted, an additive such as Al or Zn can be combined withthe REE and/or REO to promote or ensure cohesion of the rare earthelement (REE) and/or rare earth oxide (REO) particles together as wellas enhancing adhesion on the conductor surface. A volumetric ratio ofREE and/or REO to additive in the rare earth material can be in therange of about 95:5 to about 5:95 (e.g., from about 95:5 to about55:45). In example embodiments, the majority of the volume of the rareearth material consists of the REE and/or REO (i.e., the additive isprovided within the rare earth material in an amount that is less than50% by volume of the rare earth material). Example volumetric ratios ofREE and/or REO to additive within the rare earth material include,without limitation, 80:20, 75:25, 70:30, 65:35 and 60:40.

The additive can be combined with the REE and/or REO within the rareearth material in any suitable manner. In an example embodiment, REEand/or REO particles are coated with the additive (e.g., coated with Alor Zn). The coated particles are then cold spray deposited onto theconductor surface. For example, the coated particles can be providedfrom a particle feeder into a spray chamber that includes an exhaust ornozzle outlet directed toward the surface of the conductor. Theparticles are sufficiently coated so as to achieve the desiredvolumetric ratio of REE and/or REO to additive. The carrier gas isinjected into the chamber from a gas supply source at a high pressure(e.g., at a pressure of at least about 1.0 MPa, such as at least about1.5 MPa) and a suitable flow rate (e.g., at least about 1 m³/min, such aflow rate of at least about 2 m³/min) so as to eject the coatedparticles at high velocity (e.g., from about 400 m/s to about 1200 m/s)from the nozzle outlet toward the conductor surface. The spray chamberwith nozzle can be moved along the conductor surface to coat the surfacewith the rare earth material, where movement can include a single passor a plurality of passes along the entire length of the conductor. Theconductor can also be rotated so as to facilitate even coating along theouter perimeter of the conductor as the nozzle travels along the lengthof the conductor.

In another example embodiment, REE and/or REO particles and additiveparticles are provided from separate particle feeders into the spraychamber, where each type of particle is provided at a suitable flow ratewithin the spray chamber during the cold spray deposition to achieve thedesired volumetric ratio of REE and/or REO to additive within theresultant rare earth material emerging from the spray nozzle.

In further example embodiments, any suitable number of particle feederscan be provided to inject two or more REE particles and/or REO particleswithin the spray chamber, where the particles are either coated withadditive or the additive is also injected via a further particle feederwithin the spray chamber, with the flow rates from the particle feedersbeing adjusted accordingly to ensure the desired ratio of REE particlesand/or REO particles in relation to each other as well as additivewithin the resultant rare earth material emerging from the spray nozzle.

The particle sizes for the REE and REO powders, as well as the additivepowders (for embodiments in which the additive does not coat the REE andREO particles but instead is combined with REE and/or REO particles) canbe any suitable dimensions depending upon a particular type of coatingapplication process utilized. For example, for certain coatingapplication techniques such as cold spray deposition, the particle sizesfor REE and REO powders can be in the range from about 1 micrometer toabout 50 micrometers, for example from about 10 micrometers to about 50micrometers, or from about 20 micrometers to about 50 micrometers.However, other particle sizes can also be utilized for other types ofcoating application processes, including particle sizes less than about1 micrometer and also particle sizes greater than 50 micrometers (e.g.,100 micrometers or greater). The particle sizes can also vary dependingupon a particular type of REE and/or REO powder utilized, such that onetype of REE or REO has a first particle size range while another type ofREE or REO has a second particle size range. Additives such as Al or Zncan also have particle size ranges similar or different from the REEand/or REO particles of the coating powder, where the size ranges of theadditives can also be in the same ranges as noted herein for the REE andREO powders.

The coating comprising the rare earth material formed on the conductorcan have any thickness that is suitable for a particular application. Inan example embodiment, a coating thickness will be at least about 20 mil(thousands of an inch) (about 0.508 millimeter) and also will be nogreater than about 300 mil (about 7.62 millimeters).

An example cold spray deposition process suitable for depositing a rareearth material coating onto a conductor is schematically depicted inFIG. 3. In particular, one or more powder feeders 22 (e.g., feeders 22-1and 22-2 as shown in FIG. 3) provide one or more types of powders to aspray chamber/nozzle 20. As previously noted, multiple powder feeders 22may be used, e.g., for configurations in which: 1. the REE and/or REOparticles are not coated with additive, such that the REE/REO andadditive powders are provided to the spray chamber/nozzle 20 in separatepowder feeders 22 (e.g., feeders 22-1 and 22-2); and/or 2. two or moretypes of REE and/or REO particles (coated or uncoated with additive) areto be provided separately within the spray chamber/nozzle 20. A highpressure gas source 24 (e.g., a source of nitrogen or helium) alsoprovides the high pressure gas to the spray chamber/nozzle 20. As shownin FIG. 3, spray chamber/nozzle 20 has a converging-to-diverging (CD)cross-sectional profile (in the direction of particle/gas flow) toaccelerate the particulate/gas flow to supersonic velocity upon emergingfrom the nozzle outlet and toward a surface 6 of a conductor. It isfurther noted that the locations of components and orientations ofinjection of the gas and powders into the spray chamber/nozzle 20 aredepicted for example purposes only in FIG. 3, and the cold spraydeposition equipment is not limited to such orientations to achieve thedeposition of the rare earth material upon the conductor surface 6. Thedashed arrows in FIG. 3 further show possible directions at which thespray chamber/nozzle 20 can be moved to achieve a substantially uniformdeposition of rare earth material onto the conductor surface. Inaddition, the conductor can be rotated during operation (e.g., asindicated by the rotational arrow in FIG. 3) to facilitate coating ofsurface portions of or the entire peripheral surface of the conductor.Further still, multiple spray nozzles can also be utilized to achieve adesired coating thickness over some or all of the outer peripheralsurface of the conductor.

The coating compositions can be used for any suitable types ofconductors, particularly for elongated (e.g., continuously extending)conductors having rounded or other non-planar surfaces upon which thecoating composition is adhered. The conductors include a central portionor core that includes at least one conductive filament, where eachconductive filament comprises a conductive metal material such as steel,copper and/or aluminum. In some embodiments, the conductor core includesa plurality of bundled conductive filaments arranged in one or morebands or layers in relation to a central axis of the core.

Example embodiments of conductors are overhead conductors typically usedin power transmission lines, such as aluminum conductor steel supported(ACSS) cable of the round wire (RW) type or trap wire (TW) type. Otherexample embodiments of conductors include one or more conductive strandsor wires twisted around one or more other conductive strands to form thecore member, such as a cable conductor commercially available under thetrademark VR2® from Southwire Corporation (Georgia). The conductorsinclude a core member that can comprise one or more electricallyconductive strands or wires that extend the length of the conductors,where the conductive wires can be arranged in any suitableconfigurations or arrays along a central axis of the conductors. Forexample, a conductor can include a core member that comprises one ormore layers of wires, where the wires in each layer are arranged in anysuitable manner (e.g., twisted with each other, wrapped together in thelayer with each other, etc.). The core member can further include asingle central strand or wire at the center of the core member with oneor more layers of wires extending around the central wire. Theconductive wires can have any suitable dimensions, including wireshaving cross-sectional dimensions (i.e., a dimensions transverse thelength of the wires, such as diameters for wires having circularcross-sections) that are from about 1 mm or smaller to about 5 cm orgreater. The outer transverse cross-section (e.g., outer diameter) of aconductor can also vary considerably based upon a particularapplication, where some conductors can have diameters of about 5 cm orsmaller to about 30 cm or greater.

An example embodiment of an ACSS RW cable is depicted in FIG. 1, whilean example embodiment of an ACSS TW cable is depicted in FIG. 2. In eachembodiment, the ACSS cable has a rounded or circular cross-section andincludes concentrically aligned or layered filaments or wires with acentral or core portion 2 of the cable including steel strands or wiresand one, two or more layers of aluminum strands or wires 4circumferentially aligned around the core portion of steel wires. In anexample embodiment, the aluminum wires can have a 1350-0 (fully annealedto soft) temper. The aluminum wires 4-1 have a circular or roundconfiguration as shown for the ACSS RW cable type depicted in FIG. 1,while at least some of the aluminum wires 4-2 have a generallytrapezoidal (or other multi-faceted) shape for the ACSS TW cable typedepicted in FIG. 2. The steel and aluminum wires within the cables canbe coated with an alloy or any other suitable coating to preventcorrosion and provide other protection for the wires as well as enhancepower transmission capabilities within the cables. Examples of specifictypes of ACSS RW and ACSS TW cables are commercially available from,e.g., Southwire Company (Georgia). The ACSS cables are designed for usein overhead power transmission lines, where such cables are configuredto operate continuously at elevated temperatures of up to about 250° C.without loss of strength. It is further noted that these cable types areprovided for purposes of illustration only, and the rare earth materialcoating compositions described herein are not limited to implementationwith only these cable types but instead can also be used to coat anyother types of overhead conductors (e.g., bare or covered overheadconductors) as well as other types of conductors (e.g., conductorshaving multi-faceted or non-round cross sections or other geometricalshapes). For example, the rare earth material coating compositionsdescribed herein can be utilized to coat conductors that include coremembers comprising non-metallic materials (e.g., polymer compositematerials).

Rare earth material coating compositions as described herein can beapplied to the exterior surface, or portions thereof, of conductors(e.g., to a rounded or circular exterior surface) in the same manner asdescribed herein in relation to cold spray deposition or using any othersuitable deposition technique. For example, rare earth material can beapplied to a portion of or the entire circumference of the exteriorsurface 6-1 or 6-2 of the cable types depicted in FIGS. 1 and 2 so as toform a coating layer 8 over the surface 6-1 or the surface 6-2 of asuitable thickness (e.g., a thickness from about 30 mil to about 35mil).

The conductors coated with the rare earth material coating provides anumber of benefits for the conductors including, without limitation,hydrophobic and anti-icing properties for the conductors as well ascorrosion resistance for the conductors. The coatings prevent orsignificantly inhibit the formation or long term adhering of ice to theconductors in cold climates and over a wide range of water freezingtemperatures in outdoor environments, thus enhancing or improving thestructural integrity of the conductors particularly when supported aboveground in long runs (e.g., overhead power lines).

Although the disclosed inventions are illustrated and described hereinas embodied in one or more specific examples, it is nevertheless notintended to be limited to the details shown, since various modificationsmay be made therein without departing from the scope of the inventions.Accordingly, it is appropriate that the invention be construed broadlyand in a manner consistent with the scope of the disclosure and theclaims.

What is claimed:
 1. A conductor comprising: a core comprising aplurality of conductive filaments bundled along a central axis of thecore; and a coating deposited on a surface of the core, the coatingcomprising a rare earth material that includes at least one rare earthelement selected from the group consisting of Lanthanum (La), Cerium(Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm),Europium (Eu), Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium(Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb), Lutetium (Lu), Scandium(Sc) and Yttrium (Yt); wherein the rare earth material further comprisesan additive that facilitates cohesion of the rare earth material coatedon the surface of the core, and the rare earth material coating has athickness of at least 20 mil.
 2. The conductor of claim 1, wherein therare earth material includes at least one rare earth element selectedfrom the group consisting of La, Ce, Gd, Er and Tm.
 3. The conductor ofclaim 1, wherein the rare earth material comprises at least one rareearth element in elemental form.
 4. The conductor of claim 1, whereinthe rare earth material comprises at least one rare earth oxide.
 5. Theconductor of claim 4, wherein the at least one rare earth oxidecomprises at least one of La₂O₃, CeO₂, Gd₂O₃, Er₂O₃ and Tm₂O₃.
 6. Theconductor of claim 1, wherein the additive is less than 50% by volume ofthe rare earth material.
 7. The conductor of claim 6, wherein theadditive comprises aluminum or zinc.
 8. The conductor of claim 1,wherein the rare earth material coating has a thickness of at least 30mil.
 9. The conductor of claim 1, wherein the conductor comprises anoverhead conductor.
 10. The conductor of claim 9, wherein the conductorcomprises an aluminum conductor steel supported (ACSS) cable.
 11. Aconductor comprising: a core comprising a plurality of conductivefilaments bundled along a central axis of the core; and a coatingdeposited on a surface of the core, the coating comprising a rare earthmaterial that includes at least one rare earth element selected from thegroup consisting of Lanthanum (La), Neodymium (Nd), Promethium (Pm),Samarium (Sm), Europium (Eu), Gadolinium (Gd), Dysprosium (Dy), Holmium(Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb), Lutetium (Lu), Scandium(Sc) and Yttrium (Yt).
 12. A conductor comprising: a core comprising aplurality of conductive filaments bundled along a central axis of thecore; and a coating deposited on a surface of the core, the coatingcomprising a rare earth material that includes at least one rare earthelement selected from the group consisting of Lanthanum (La), Cerium(Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm),Europium (Eu), Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium(Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb), Lutetium (Lu), Scandium(Sc) and Yttrium (Yt); wherein the rare earth material further comprisesan additive that facilitates cohesion of the rare earth material coatedon the surface of the core, and the additive comprises aluminum or zinc.